Existing equipment for separation and collection of fine powder from a gas stream, typical of the process stream of a gas atomizer apparatus for making metallic powder, employ a combination of a primary powder container fed from a concentric reducer at the bottom of the atomizer chamber and a secondary cyclone collector fed from a duct at an elevated position on the side of the atomizer chamber. Alternative separator/collector equipment utilizes the same bottom-mounted primary powder container but the secondary cyclone is fed from a duct closely coupled to the primary powder container. Still other equipment utilizes a reducer that is bottom-mounted concentric to the atomizer chamber and that feeds a curved duct leading to a primary cyclone separator/collector. The primary powder container is eliminated in such equipment. The latter type of separator/collector equipment is illustrated in the Anderson U.S. Pat. No. 5,125,574 which discloses a gas atomizing apparatus for atomizing a melt using high pressure, supersonic gas flow from an atomizing nozzle to make ultrafine, generally spherical metallic powder having a rapidly solidified microstructure.
All three types of separator/collector equipment have some advantages (e.g. passive operation and suitable collection efficiency for conventional powder sizes, such as most powders with diameters greater than 20 microns) and some disadvantages (e.g. unintended powder accumulation regions, powder contamination from cyclone wall erosion, and unsuitable collection efficiency for ultrafine powder sizes, such powders with diameters less than about 20 microns).
It is an object of the present invention to provide an improved powder separator/collector that reduces unintended powder accumulation regions that, in turn, reduce yields achievable, reduces powder contamination from equipment wall erosion, and improves collection efficiency of ultrafine powder sizes.